When a manufacturer of small-bore pneumatic cylinders decided to
automate holemaking operations, results were anything but small time.
Compact Air Products Inc, Westminster, SC, makes a broad assortment of
small-diameter pneumatic cylinders. Sizes range from 1 1/4 [inches]
square to 4.0 [inches] dia round, in lengths from 7/8 [inches] to 4.0
[inches] in several body styles.

According to company president, Larry Yuda, the decision to
automate was fairly straightforward. "We drill and tap between
20,000 and 25,000 holes per week. Each cylinder normally has two air
ports, two to four mounting holes, and two wire holes. In addition, we
drill several types of mounting hardware."

Formerly, all work was performed on a series of bench-mounted drill
presses. The sheer volume of work, combined with the accuracy demanded
of the drilling department and the amount of labor hours required, led
to the development of the factory-assembled ADMs (automatic drilling
machines).

Although many people relate dedicated drilling machines to
high-volume operations, typical production quantity for Compact Air in a
given size is 50 to 250 pieces.

Faced with the classic "make or buy" decision, Yuda
decided that his engineering department could design the machine, and
his shop could build it at a lower cost and with less lead time than
required from outside machine-tool builders. Machine bases were
fabricated from 2 [inches] plate stock, but the real key was in locating
drilling spindles that had the required speed and accuracy for
high-volume, close-tolerance holemaking. The company chose a series of
automatic modular drilling machines made by Suhner Industrial Products
Corp.

Each of four machining tables is set up with three SUmatic
self-feed drill units. Generally, each table is designed to accommodate
a particular size range of products.

Two of the four work stations are dedicated to standard production
drilling, while the third station includes an additional spindle to
facilitate left-hand or right-hand ported cylinders. Simply by turning a
switch, the operator is able to produce the left-hand version of a
standard cylinder.

The fourth station performs the largest range of drilling
operations. This station features a programmable peck-feed controller,
thus enabling the operator to select a one-, two- or three-stage
drilling process.

One major feature of the system is the ability to change tooling
quickly to accommodate production shifts. Changeover is accomplished
simply by changing drill sizes and collets. Multi-drill heads allow for
rapid changeover with minimum downtime. Since many orders call for some
type of customization, this ability to respond rapidly has been a major
factor in the success of the company.

Aluminum cylinder bodies are manually placed in parts fixtures.
From that point, all work is automated. Compact Air Products used its
own cylinders to clamp and secure the workpiece in place. Each of three
spindles work simultaneously while sensors monitor the process, so that
drills cannot operate when the workpiece is not in proper position.

In commenting on the success of the operation and on the
performance of the ADMs, Mr Yuda states that "this system allows us
to perform in minutes what formerly would have taken a month to do
manually." Drilling accuracy is also improved, and, with respect to
reliability, one drilling center is equipped with a counter that
currently shows over 75,000 cylinders that have been successfully
machined.

Compact Air still uses the bench-mounted drill presses for
special-purpose and nonstandard cylinders that account for about 30
percent of its orders, and for robotic grippers that account for a
growing percentage of its total product line.